1. Field of the Invention
The present invention relates to a rotary wheel for a ball pitching machine and, more particularly, to a rotary wheel structure used in a baseball or softball pitching machine.
2. Description of the Related Art
A general ball pitching machine includes one or two rotary wheels driven by a motor and provides batting practice or defense practice by shooting baseballs or softballs.
FIGS. 1 and 2 illustrate a conventional rotary wheel 10 for a ball pitching machine. The rotary wheel 10 includes a circular wheel body 12, a resilient member 14 fitted around an outer periphery of the wheel body 12, and a sleeve 16 engaged to a center of the wheel body 12. The wheel body 12, the resilient member 14, and the sleeve 16 are unified into a one-piece construction. Manufactured with resilient material such as urethane in general, the resilient member 14 contacts a ball during rotation of the rotary wheel 10 to create a frictional force and pitch the ball. The sleeve 16 is generally manufactured with a metal material and has a central shaft hole 18 to be penetrated by and coupled with a shaft of a motor (not shown), so that the rotary wheel 10 can be driven by the motor. In a course of pitching one ball, the resilient member 14, however, is compressed to make the plastic wheel body 12 suffer from compression-induced shocks, such that the wheel body 12 is easily broken or damaged as well as the sleeve 16 may be easily separated from the wheel body 12. Finally, the conventional rotary wheel 10 will not be driven to turn by the motor when the sleeve 16 is separated from the wheel body 12.